1. Field of the Invention
The present invention relates to a radio communication system, and more particularly, to a method and apparatus for channel estimation for radio link between a base station and a relay station in a radio communication system supporting multiple carriers.
2. Discussion of the Related Art
FIG. 1 shows a relay node (RN) 120 and User Equipments (UEs) 131 and 132 located in an area of one base station (or eNodeB or eNB) 110 in a radio communication system 100. The RN 120 may transmit data received from the eNodeB 110 to the UE 132 located in an RN area and transmit data received from the UE 132 located in the RN area to the eNodeB 110. In addition, the RN 120 may expand a high data rate area, improve communication quality in a cell edge, and support provision of communication in a building or in an area other than a base station service area. In FIG. 1, the UE 131 (hereinafter, referred to as a macro-UE or M-UE) which directly receives a service from the eNodeB and the UE 132 (hereinafter, referred to as a relay-UE or R-UE) which receives a service from the RN 120 are shown.
A wireless link between the eNodeB and the RN is called a backhaul link. A link from the eNodeB to the RN is called a backhaul downlink and a link from the RN to the eNodeB is called a backhaul uplink. In addition, a wireless link between the RN and the UE is called an access link. A link from the RN to the UE is called an access downlink and a link from the UE to the RN is called an access uplink.